Methods, algorithms, software, circuits, architectures, and systems for improved communications over cyclostationary channels

ABSTRACT

Methods, software, receivers and systems for communicating information over a cyclostationary channel. The method generally includes interleaving sections of a control sequence with bits of the information. The software and receivers are generally configured to implement one or more aspects of the methods disclosed herein, and the systems generally include those that embody the inventive receivers disclosed herein. The present invention is particularly useful in powerline channels, where certain parameters (such as noise) have time-dependent or periodic variations in value. By distributing the control sequence, the incidence of carrier recovery is reduced, the likelihood of successful packet or frame transmissions is increased, and data may be more reliably communicated.

FIELD OF THE INVENTION

The present invention generally relates to the field of communications(e.g., information transmissions). More specifically, embodiments of thepresent invention pertain to methods, algorithms, software, circuits,architectures, and systems for information transmissions over channelsthat have time-dependant or periodic fluctuations.

DISCUSSION OF THE BACKGROUND

Communications systems or networks generally comprise channels forsending and receiving data, audio and/or video information. A number ofwired communications systems or networks, such as cable, Ethernet andGigabit Ethernet systems, generally include stationary channels. Astationary channel is generally one in which the channel response andthe noise statistics do not vary significantly or regularly (if at all)over time. Techniques are available for such systems and networks toreduce the adverse effects of random and/or systematic fluctuations incommunications parameters. However, such techniques generally do notaffect communications parameters that tend to fluctuate over time.

Certain communications systems or networks, such as powerline systems ornetworks, include cyclostationary channels. A cyclostationary channel isone in which the channel response, the noise statistics and/or channelattenuation vary periodically. Also, powerline channels, which useconventional AC power lines for communications, experience regularfluctuations in noise and signal attenuation. The period of the noisepower function in a powerline channel is generally the inverse of twiceits frequency. In a typical case, that period is (1/120 Hz), or 8.3msec. Noise in a powerline channel may also be introduced by othersources. During “spikes” in the noise power in a powerline channel, thesignal-to-noise ratio (SNR) can be reduced sufficiently to cause errorsin the data. Particularly when the signal strength is low, a low SNR cancause significant reliability problems.

Referring now to FIG. 1, the powerline transmits a 60 Hz or 50 Hzsinusoidal power signal 10 supplying AC. The noise 20 in power lines maychange within a period T_(AC) or T_(AC)/2, where T_(AC) is the durationof one cycle of the AC power supply and/or voltage, typically 1/60 or1/50 seconds (see, e.g., “Modeling of Cyclostationary and FrequencyDependent Power-Line Channels for Communications,” by Katayama et al.).As shown in FIG. 1, under common normal operating conditions, powerlinechannel noise 20 typically comprises a “zero power” component 30(representative of the noise in the channel at the points where the ACpower curve 10 crosses the zero power axis 15) and a burst noisecomponent 40 (representative of the noise in the channel where the ACpower curve 10 is at or near its maximum value[s]), although noise incyclostationary channels may vary, depending upon operating conditions,equipment, power supply variations, etc. Thus, under normal operatingconditions, cyclostationary channel noise 20 may be somewhat related tothe absolute value of the AC power signal 10.

A typical packet 100 for burst mode transmission is shown in FIG. 2. Thepacket 100 typically comprises a preamble 110, a synchronizationsequence (or “syncmark”) 120, and data 130. The synchronization sequence120 is used during frame synchronization. Under burst noise, especiallycyclostationary burst noise, there is a relatively high probability thatbits in the synchronization sequence 120 may be corrupted. For 10 Kb/sDBPSK modulation (0.1 ms/bit), if the cyclostationary noise has a burstlength of half of its cycle (i.e., half of T_(AC)/2=4.15 ms for 60 Hz ACpower), about 42 bits could be corrupted by cyclostationary burst noise.This implies that the synchronization sequence 120 should be longer, andperhaps significantly longer, than 42 bits.

In systems without burst noise, the preamble 110 is often a 010101sequence, and it is often used in carrier recovery. Due to the long,cyclostationary burst noise on the powerline, it is possible that theentire preamble 110 can be corrupted by burst noise, which means a verylong preamble (e.g., more than 4.2 ms, or 42 bits at a 10 Kb/s rate) isdesirable in a 60 Hz powerline channel to improve the success rate incarrier recovery. However, it is naturally desirable to minimize thenumber of bits dedicated to non-data (e.g., control and/oridentification) functions, particularly over a sometimes noisy and/orproblematic medium such as power lines. In some applications (e.g.,voice transmissions), one might wish to completely avoid transmittinginformation during periods of high noise, and thus, one might keep thepacket length small to fit packets into the “low noise” periods on thepower line.

A need therefore exists to improve communications in channels in whichtime-dependant fluctuations are a potential source of error orcorruption, in order to reduce errors, reduce shutdowns, increase thesuccess rate of such communications and/or increase communicationsuptime in networks that include such channels.

SUMMARY OF THE INVENTION

Embodiments of the present invention relate to methods, algorithms,software, circuitry (e.g., receivers), architectures, and systems forimproving communications (particularly data communications) overchannels having time-dependant or periodic fluctuations. The method ofcommunicating information generally comprises the steps of (a)interleaving a plurality of sections of a control sequence with bits ofthe information; and (b) transmitting the interleaved control sequencesections and the information over a channel having periodicallyrecurring and/or time-dependent parameter fluctuations. The method ofreceiving and/or processing information generally comprises the steps of(1) receiving a block of information from a channel having periodicallyrecurring and/or time-dependent parameter fluctuations, the block ofinformation further comprising a plurality of interleaved sections of acontrol sequence; (2) identifying the interleaved synchronization marksections; and (3) processing the block of information. The algorithmsand/or software are generally configured to implement one or moreaspects of the inventive methods disclosed herein.

In one embodiment, the receiver circuitry and/or architecture generallycomprise (A) a recovery circuit configured to recover an informationsignal from a channel; (B) a channel parameter monitor configured todetermine, directly or indirectly, a value for a first parameter of thefirst channel, the first parameter having one or more periodicallyrecurring and/or time-dependant fluctuations; and (C) logic configuredto process the recovered information signal in a manner dependent on thefirst parameter value. In another embodiment, the receiver circuitryand/or architecture generally comprise (i) a recovery circuit configuredto recover an information signal from a channel having one or moreperiodically recurring and/or time-dependant parameter fluctuations;(ii) a storage circuit configured to store a control sequence patterncomprising a plurality of interleaved sections; and (iii) logicconfigured to identify the control sequence pattern in the informationsignal. The systems generally comprise those that include a circuitand/or architecture embodying one or more of the inventive conceptsdisclosed herein.

The present invention advantageously provides improved reliability indata communications. The present invention is particularly useful incyclostationary channels, such as powerline channels, where certainparameters have time-dependent or periodic variations in value. Theseand other advantages of the present invention will become readilyapparent from the detailed description of preferred embodiments below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing various powerline waveforms.

FIG. 2 is a diagram showing a conventional data communication packetformat.

FIG. 3 is a diagram showing an exemplary data communication packetformat according to the present invention.

FIG. 4 is a diagram showing a powerline burst noise waveform, a portionof an exemplary powerline packet format according to the presentinvention, and waveforms at certain nodes in the circuit of FIG. 7.

FIG. 5 is a diagram showing an exemplary synchronization mark detectionscheme according to the present invention.

FIG. 6 is a diagram showing an exemplary “mark and omit” schemeaccording to the present invention for improving the reliability ofsynchronization mark detection.

FIG. 7 is a box-level diagram showing a first embodiment of the presentreceiver circuitry.

FIG. 8 is a box-level diagram showing a second embodiment of the presentreceiver.

FIG. 9 is a box-level diagram showing an exemplary transmitter.

FIG. 10 is a diagram showing an exemplary communication system.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the preferred embodiments of theinvention, examples of which are illustrated in the accompanyingdrawings. While the invention will be described in conjunction with thepreferred embodiments, it will be understood that they are not intendedto limit the invention to these embodiments. On the contrary, theinvention is intended to cover alternatives, modifications andequivalents, which may be included within the spirit and scope of theinvention as defined by the appended claims. Furthermore, in thefollowing detailed description of the present invention, numerousspecific details are set forth in order to provide a thoroughunderstanding of the present invention. However, it will be readilyapparent to one skilled in the art that the present invention may bepracticed without these specific details. In other instances, well-knownmethods, procedures, components, and circuits have not been described indetail so as not to unnecessarily obscure aspects of the presentinvention.

Some portions of the detailed descriptions which follow are presented interms of processes, procedures, logic blocks, functional blocks,processing, and other symbolic representations of operations on databits, data streams or waveforms within a computer, processor, controllerand/or memory. These descriptions and representations are generally usedby those skilled in the data processing arts to effectively convey thesubstance of their work to others skilled in the art. A process,procedure, logic block, function, operation, etc., is herein, and isgenerally, considered to be a self-consistent sequence of steps orinstructions leading to a desired and/or expected result. The stepsgenerally include physical manipulations of physical quantities.Usually, though not necessarily, these quantities take the form ofelectrical, magnetic, optical, or quantum signals capable of beingstored, transferred, combined, compared, and otherwise manipulated in acomputer or data processing system. It has proven convenient at times,principally for reasons of common usage, to refer to these signals asbits, waves, waveforms, streams, values, elements, symbols, characters,terms, numbers, or the like.

It should be borne in mind, however, that all of these and similar termsare associated with the appropriate physical quantities and are merelyconvenient labels applied to these quantities. Unless specificallystated otherwise and/or as is apparent from the following discussions,it is appreciated that throughout the present application, discussionsutilizing terms such as “processing,” “operating,” “computing,”“calculating,” “determining,” “manipulating,” “transforming,”“displaying” or the like, refer to the action and processes of acomputer or data processing system, or similar processing device (e.g.,an electrical, optical, or quantum computing or processing logic,circuit or device), that manipulates and transforms data represented asphysical (e.g., electronic) quantities. The terms refer to actions,operations and/or processes of the processing devices that manipulate ortransform physical quantities within the component(s) of a system orarchitecture (e.g., registers, memories, other such information storage,transmission or display devices, etc.) into other data similarlyrepresented as physical quantities within other components of the sameor a different system or architecture.

Furthermore, for the sake of convenience and simplicity, the terms“clock,” “time,” “rate,” “period” and “frequency” are generally usedinterchangeably herein and are generally given their art-recognizedmeanings, but use of any one of these terms will generally indicate thesuitability of any of the other of these terms. Also, for convenienceand simplicity, the terms “data,” “data stream,” “waveform” and“information” may be used interchangeably, as may the terms “mark” and“tag” (and grammatical variations thereof), and the terms “connectedto,” “coupled with,” “coupled to,” and “in communication with” (any ofwhich may be direct or indirect).

In the present disclosure, except where the context clearly indicatesanother meaning, the terms “distribute” and “interleave” (andgrammatical variations thereof) are used interchangeably, and use of oneof these terms will generally indicate the suitability of the other. Inaddition, the terms “packet” and “frame” are also used interchangeably,and use of one term will generally indicate the suitability of theother, although these two terms are generally given their art-recognizedmeanings. The term “adjacent” has its art-recognized meaning, but theterm “proximate” means close or nearby, and includes (but is not limitedto) “adjacent.”

The present invention concerns methods, software, receivers and systemsfor communicating information over a cyclostationary channel (e.g., thathas periodically recurring and/or time-dependant processing and/orparameter fluctuations). The method of communicating informationgenerally comprises the steps of (a) interleaving a plurality ofsections of a control sequence with bits of the information; and (b)transmitting the interleaved control sequence sections and theinformation over a channel having periodically recurring and/ortime-dependent parameter fluctuations. The method of receiving and/orprocessing information generally comprises the steps of (1) receiving ablock of information from a channel having one or more periodicallyrecurring and/or time-dependent parameter fluctuations, the block ofinformation further comprising a plurality of interleaved sections of acontrol sequence; (2) identifying the interleaved synchronization marksections; and (3) processing the block of information. The algorithmsand/or software are generally configured to implement one or moreaspects of the inventive methods disclosed herein.

In one embodiment, the receiver circuitry and/or architecture generallycomprise (A) a recovery circuit configured to recover an informationsignal from a channel; (B) a channel parameter monitor configured todetermine, directly or indirectly, a value for a channel parameterhaving periodically recurring and/or time-dependant fluctuations; and(C) logic configured to process the recovered information signal in amanner dependent on the channel parameter value. In another embodiment,the receiver circuitry and/or architecture generally comprise (i) arecovery circuit configured to recover an information signal from achannel having one or more periodically recurring and/or time-dependantparameter fluctuations; (ii) a storage circuit configured to store acontrol sequence pattern comprising a plurality of interleaved sections;and (iii) logic configured to identify the control sequence pattern inthe information signal. The systems generally comprise those thatinclude a circuit and/or architecture embodying one or more of theinventive concepts disclosed herein.

The periodically recurring and/or time-dependent parameters (hereinaftersimplified as “time-dependent parameters”) for which the presentinvention is applicable include noise parameters (such as harmonic noiseof nearly any kind, and in nearly any kind of channel), power parameters(such as signal modulation, channel attenuation and/or power factorcontrol parameters), and others (such as zero sequence current). Thus,the time-dependent parameter in the present invention is not limited tonoise power in a powerline channel. The invention, in its variousaspects, will be explained in greater detail below with regard toexemplary embodiments.

Exemplary Methods of Transmitting a Block of Information Over aCyclostationary Channel

In one aspect, the present invention relates to methods for processinginformation transmissions over a channel having time-dependent and/orperiodic parameter fluctuations. In one sub-aspect related to sendinginformation over the channel, the method comprises the steps ofinterleaving a plurality of sections of a control sequence with bits ofthe information, and transmitting the interleaved control sequencesections and the block of information over the channel. In anothersub-aspect related to receiving the transmission, the method comprisesthe steps of receiving the block of information from the channel, theblock of information further comprising a plurality of interleavedsections of a control sequence; identifying the interleaved controlsequence sections; and processing the block of information.

In a preferred embodiment, the channel comprises a cyclostationarychannel, and the time-dependent parameter may comprise a noiseparameter, an energy parameter, a power parameter, or an attenuationparameter. However, referring back to FIG. 1, burst noise is asignificant source of potential error in a cyclostationary channel, suchas a powerline channel, and the present invention is particularly suitedfor improving the reliability of information transmissions overcyclostationary channels where burst noise can mask (or otherwise renderunreliable) relatively short sequences of information, such as controlsequences in a packet or frame.

FIG. 3 shows an exemplary architecture for a block of information 200 tobe communicated according to the present invention. The information maycomprise data, audio (voice) and/or video information. In oneembodiment, the information comprises data, and in variousimplementations, the block of information comprises a data packet or aframe comprising data. However, for convenience and simplicity, theterms, “data” and “information” will be used interchangeably herein.

Exemplary information block 200 generally comprises a preamble 210, aplurality of control sequence sections 220, 222, 224 and 226,interleaved data 230, 232 and 234, and terminal (typically bulk)information portion or segment 236. In the example of FIG. 3, thecontrol sequence 220-226 comprises a synchronization sequence or mark(“SYNCMARK”), but in general, it may comprise any control sequenceconventionally used in information communications, such as a preamble, aheader sequence, a start-of-frame sequence, a start-of-packet sequence(which may be equivalent to and/or interchangeable with thesynchronization mark or sequence), address information (such as sourceor destination information), encryption information, an error checkingsequence (such as CRC code or Hamming code) or an identificationsequence.

Continuing to refer to FIG. 3, the exemplary control sequence comprisesfirst control sequence section 220 (“SM_(0-a)”), second control sequencesection 222 (“SM_(b-c)”), third control sequence section 224(“SM_(d-e)”) and fourth control sequence section 226 (“SM_(f-g)”). Whilefour such sections are shown, the control sequence can be divided intoany integer number of sections of two or more, up to the number of bitsin the control sequence. Thus, the control sequence generally has alength of n bits and comprises m sections, where each of n and m areindependently an integer of at least 2, and n≧m.

Also, the length of each control section can be independent of the othersections' lengths. In other words, each of the sections of the controlsequence independently has a length of from 1 to (n−m) bits. Forexample, assuming each control sequence section 220, 222 224 and 226 inFIG. 3 has a length of at least two bits, “a” in SM_(0-a) 220 can be anyinteger of from 1 to (g−1), where g is the last bit position of thefinal control sequence section SM_(f-g) 226 and g=(n−1). The differencesc−b in SM_(b-c) 222 (b=a+1), e−d in SM_(d-e) 224 (d=c+1), and g−f inSM_(f-g) 226 (f=e+1) can independently be any integer of from 0 to(n−m−1), as long as (a+c+e+g−b−d−f+4)=n. In one embodiment, each controlsequence section has a length as close to the lengths of the othersections as is possible (i.e., a length of n/m when n is an integermultiple of m, or a length of a nearest integer to n/m when n is not aninteger multiple of m). In one implementation, each control sequencesection has a length of two bits (unless the control sequence has an oddnumber of bits, in which case the last section has a length of one bit).Thus, where n is an even integer of at least 4, m may be an integer offrom 2 to (n/2), and each of the control sequence section lengths isindependently from 2 to (n/2) bits. Alternatively, where n is an oddinteger of at least 5, m may be an integer of from 2 to ((n−1)/2), andeach of the control sequence section lengths is independently from 2 to((n+1)/2) bits.

Where the control sequence comprises or consists of a synchronizationmark, the synchronization mark may have a length of at least 4 or 6 bitsand/or up to 20, 30 or 40 bits. In one implementation, thesynchronization mark has a length of 10 bits (g=9 in SM_(f-g)). Thus,“a” in SM_(0-a) 220 may be 1 or 2; b and c in SM_(b-c) 222 may be 2 or 3and 3, 4 or 5, respectively; d and e in SM_(d-e) 224, may be 4, 5 or 6and 5, 6 or 7, respectively; and f in SM_(f-g) 226 may be 7 or 8.

Interleaved data segments or portions 230, 232 and 234 generally have alength that is selected such that transmission of the combined controlsequence sections 220-226 and interleaved data segments 230-234 takeslonger that T_(AC)/2 (as defined above). Generally, interleaved datasegments 230-234 have a length about the same as or greater than thoseof the corresponding control sequence sections 220-226. For example,each interleaved data segment may independently have a length of from 2,4 or 6 bits to 10, 20, 40 or 100 bits. Terminal information segment 236typically comprises the bulk of the non-control information in block200, usually at least half of such non-control information andfrequently as much as 70%, 80%, 90% or more of such non-controlinformation.

As shown in the exemplary embodiment of FIG. 3, the block of information200 may further comprise a preamble 210, in which case the methodfurther comprises transmitting the preamble. Certain implementations mayuse phase shift keying (e.g., quadrature PSK) and/or differentialmodulation (DBPSK, for example) to avoid carrier recovery (see, e.g.,Proakis, J., “Digital Communications,” McGraw-Hill Companies, Inc.[2000]). Therefore, a very short preamble (e.g., from 4 to 10 bits, andin one implementation, 6 bits) may be used. However, other modulationtechniques, such as amplitude modulation and code shift keying (each ofwhich may be differential), may also be employed.

While the present method of sending information is not limited by therate at which the information is sent, transmitting may be conducted ata rate of at least about 5 KHz or about 10 KHz, up to about 1 MHz, about10 MHz, about 100 MHz, about 1 GHz, about 2.5 GHz, or even about 5 GHz.However, in the case of powerline channels, where the standard ACfrequency is generally about 50 Hz or 60 Hz, the time-dependentparameter fluctuations generally have a period of no more than T_(AC)/2,or about 8.3 msec (in the case of 60 Hz AC power) or about 10 msec (inthe case of 50 Hz AC power). Thus, as described above, sections of thecontrol sequence may be interleaved with bits of the information over aperiod of time of at least T_(AC)/2, or about 8.3 msec to about 10 msecin a powerline channel.

However, as shown in FIG. 1, the time-dependent noise fluctuations in apowerline channel have a minimum period of T_(AC)/2, but burst noisesignal 40 has a length that is smaller than T_(AC)/2. Due to variationsin operating conditions (e.g., fluctuations in power supply, signalprocessing, etc.), the length of burst noise 40 may be characterized asa fraction of T_(AC) smaller than that of the time-dependent noisefluctuations (e.g., from about T_(AC)/6 to about T_(AC)/3, and in oneembodiment, about T_(AC)/4). Thus, in further embodiments of the presentinvention, sections of the control sequence may be interleaved with bitsof the information over a period of time of at least about 8.3 msec, 5.6msec, 4.2 msec or 2.8 msec in the case of 60 Hz AC power, and about 10msec, 6.7 msec, 5 msec or 3.3 msec in the case of 50 Hz AC power. Byinterleaving sections of the control sequence during at least asubstantial portion of the time-dependent parameter fluctuation function(e.g., burst noise function 40), at least some part of the controlsequence is likely to be transmitted during a period when that channelparameter is at a relatively low value.

Exemplary Methods of Receiving a Block of Information from aCyclostationary Channel

In an aspect of the invention related to receiving a block ofinformation from a channel having time-dependent parameter fluctuations,the method generally comprises the steps of: receiving the block ofinformation from the channel; identifying the interleavedsynchronization mark sections; and processing the block of information.As for the method of transmitting, the block of information comprises aplurality of interleaved sections of a control sequence, and/or theinformation may comprise data or audio and/or visual (video or still)information. In various embodiments, the block of information comprisesa data packet or frame comprising data, and/or the control sequencecomprises a synchronization mark. In the latter embodiment, the methodfurther comprises the steps of identifying the synchronization mark, andsynchronizing a first bit of the block of information to a predeterminedreference (i.e., a known value or sequence for the control sequence).

In one embodiment, the method of receiving information further comprisesthe step of searching for the interleaved sections of the controlsequence in response to transmission energy in the channel exceeding apredetermined threshold energy. Thus, the method may also furthercomprise (i) determining and/or calculating a channel transmissionenergy, and/or (ii) comparing a channel transmission energy with athreshold energy.

FIG. 4 shows an exemplary “threshold channel energy” control sequencesearching embodiment. Channel noise 300 varies or fluctuates regularlyas a function of time, as is known, for example, in powerline channels.A packet 310, comprising preamble 312, synchronization mark sequencesections SM₀ 320, SM₁ 322 and SM₂ 324, and interleaved data segments 330and 332, is received from the channel. However, the first bit ofpreamble 312 is received during a burst noise maximum 305, thusincreasing channel transmission energy 340 by a relatively smallincrement 342 at a relatively high range of values. Such a transitioncan be difficult to detect using technology in existence prior to thepresent invention.

The “threshold channel energy” control sequence searching embodiment ofthe present invention avoids the difficulties associated with trying todetect a relatively small increase in channel transmission energy atrelatively high energies. Instead, one determines or calculates thetotal channel transmission energy 340 (using known techniques andcircuits), compares the transmission energy 340 with a predeterminedthreshold energy 345, then initiates a search for the interleavedsections 320, 322 and 324 of the control sequence when the transmissionenergy 340 exceeds a predetermined threshold energy 345. The search maybe initiated by asserting a synchronization mark or start-of-packet(“SOP”) search or detection enable signal, such as “SOP Detect” signal350, which essentially activates logic and/or circuitry that searchesfor (or attempts to detect) the sections 320, 322 and 324 of the controlsequence.

In the example of FIG. 4, after burst noise maximum 305, transmissionenergy 340 (which is representative of zero sequence noise 307 andpacket 310) decreases to a value slightly greater than threshold energy345. Thus, the example of FIG. 4 will also search for the controlsequence sections in response to receiving the information block whenthe time-dependent channel parameter fluctuation is at a relativeabsolute minimum. However, one may select a different threshold energyfor initiating detection of the control sequence, as may be empiricallydetermined in accordance with techniques known to those skilled in theart.

FIG. 5 shows a set of exemplary waveforms for the present controlsequence searching and/or detection scheme. As described above withrespect to FIG. 4, one may detect the packet arrival by detecting atransmission band energy increase, but the transmission band energycould also increase due to burst noise. Therefore, the search range forthe control sequence may be extended to encompass both possibilities fortransmission band energy increases, a technique that can be designated“extended frame search range” for convenience.

Referring back to FIG. 5, for each search location (corresponding toeach bit, in order, in demodulated information stream 410), one maycompare (or cross-correlate) the received bit stream 410 with thereference control sequence (e.g., syncmark pattern 420). (As isunderstood by those skilled in the art, the received and/or demodulatedinformation may be in the form of a single-ended or differential analogwaveform, and such received and/or demodulated information may besampled according to known techniques to generate or produce acorresponding bit stream comprising discrete units of data having one ofa plurality of digital logic levels.) For example, one may calculate acorrelation coefficient for a first sequence 412 of bit stream 410(e.g., starting at search position 1) having the same length as thecombined control sequence sections and interleaved data. The correlationcoefficient is generally calculated using only the bit positionscorresponding to the control sequence (e.g., syncmark) sections SM₀₋₁422, SM₂₋₃ 424, SM₄₋₅ 426 and SM₀₋₁ 428, as shown in FIG. 5. While FIG.5 shows a synchronization mark having a length of eight bits, dividedevenly into four sections and interleaved with data segments of two bitseach, one may use any type of control sequence having nearly any length,divided into nearly any number of sections (but not to exceed the numberof bits in the control sequence), and interleaved with data segments ofany appropriate length (e.g., as discussed above).

This correlation coefficient calculation may be repeated for the nextposition of bit stream 410 (e.g., using second sequence 414), then foreach successive position of bit stream 410 up to the sequence 418 at thelast position of bit stream 410 (defined as that position occurring atthe end of a search period T_(search) 430). The sequence having aminimum correlation distance (e.g., a minimum Hamming or Euclideandistance) may then be selected to identify the location of the controlsequence. Thus, in further embodiments, the searching step may comprisecalculating a correlation coefficient and/or a minimum correlationdistance between (1) the interleaved sections of the control sequenceand (2) the received information. While the minimum correlation distancecalculation is largely conventional, a Hamming distance calculation maybe preferred in certain implementations. In the example of FIG. 5,T_(search) 430 is longer than the maximum length of the burst noise,which generally is considered to be half of T_(AC)/2.

A further embodiment of the invention relates to use of an adjacentreference band to mark bits that are received when the time-dependentparameter fluctuations exceed a predetermined and/or threshold value. Incyclostationary channels such as powerline channels, proximate oradjacent frequency bands often have cyclostationary parameters (such asburst noise) with characteristics similar to those of the band in whichinformation is being received. For example, if one receives a channeltransmission at 10 KHz, one can monitor channel noise at 5 KHz, 15 KHzor 20 KHz and get a reasonably reliable and/or accurate estimate of thechannel noise at 10 KHz. Similarly, if one receives a channeltransmission in the 250-300 KHz band, one can monitor channel noise in200-250 KHz or 300-350 KHz bands and get a reasonable estimate of thechannel noise value in the 250-300 KHz band. Therefore, one canindirectly determine or detect such parameter excursions in atransmission band by observing or monitoring the same parameter in aproximate or adjacent frequency band.

Thus, the present method may further comprise comparing a transmissionenergy from a second band of the channel (or even a second, structurallyand/or functionally similar or identical channel) with a thresholdenergy, the second band or channel being proximate to the first band orchannel, and having at least one substantially similar time-dependentparameter fluctuation to those of the first band or channel. In variousembodiments, the parameter being monitored or observed is transmissionenergy and/or noise (e.g., burst noise).

An even further embodiment of the invention relates to use of areference band (or channel) parameter marker as an erasure indicator (or“tag”). For example, when the energy in the reference band is over acertain threshold level, one may expect similar or substantially thesame noise in the transmission band. Therefore, when the energy in thereference band is over a certain threshold level, one can mark or “tag”the bits transmitted at the same time over the transmission channel asun-reliable bits. For control sequence (e.g., syncmark) search andcomparison, the marked bits can be ignored, and the bit stream sequencestarting at the position with the largest number of matched, unmarkedbits relative to the reference control sequence can be selected as theinitial control sequence location. Thus, the present method may furthercomprise the step(s) of (i) marking bits received from the first band orchannel as unreliable when the transmission energy from the second bandor channel exceeds the threshold energy; and/or (ii) identifying theinterleaved sections of the control sequence from unmarked bits in theinformation received from the first band or channel.

FIG. 6 shows a set of exemplary waveforms for the present “bit marking”scheme 500. For example, a bit stream 510 is received from a firstfrequency band of a cyclostationary (e.g., powerline) channel. A noiseor transmission energy parameter of a second frequency band of thecyclostationary channel adjacent to the first frequency band ismonitored and compared to a threshold energy level to produce a markingwaveform r, 520. When the noise or transmission energy of the secondfrequency band exceeds the threshold energy level, marking waveformr_(n) 520 changes state to an active bit marking logic level 522, 524and 526 at bit positions X₂, X₃, X₅ and X₁₃-X₁₆. Thus, the bits in bitstream 510 at positions X₂, X₃, X₅ and X₁₃-X₁₆ will be marked asunreliable and will be ignored in any subsequent control sequencesearch, calculation and/or determination.

Exemplary Software

The present invention also includes algorithms, computer program(s)and/or software, implementable and/or executable in a general purposecomputer or workstation equipped with a conventional digital signalprocessor, configured to perform one or more steps of the method and/orone or more operations of the hardware. Thus, a further aspect of theinvention relates to algorithms and/or software that implement the abovemethod(s). For example, the invention may further relate to a computerprogram, computer-readable medium or waveform containing a set ofinstructions which, when executed by an appropriate signal processingdevice, is configured to perform the above-described method and/oralgorithm.

For example, the computer-readable medium may comprise any medium thatcan be read by a signal processing device configured to read the mediumand execute code stored thereon or therein, such as a floppy disk,CD-ROM, magnetic tape or hard disk drive. Such code may comprise objectcode, source code and/or binary code.

The waveform is generally configured for transmission through anappropriate medium, such as copper wire, a conventional twisted pairwireline, a conventional network cable, a conventional optical datatransmission cable, or even air or a vacuum (e.g., outer space) forwireless signal transmissions. The waveform and/or code for implementingthe present method(s) are generally digital, and are generallyconfigured for processing by a conventional digital data processor(e.g., a microprocessor, microcontroller, or logic circuit such as aprogrammable gate array, programmable logic circuit/device orapplication-specific [integrated] circuit).

In various embodiments, the present computer-readable medium or waveformmay be adapted so that the block of information comprises (i) a preamble(optional) and (ii) a data packet or frame comprising data, and/or thecontrol sequence comprises a synchronization mark, a header sequence, astart-of-frame sequence, a start-of-packet sequence, addressinformation, encryption information, an error checking sequence or anidentification sequence. In certain implementations, the controlsequence comprises a synchronization mark and may further comprise apreamble. Thus, the instructions in the present computer-readable mediumor waveform may be configured to perform the step of placing a preamblebefore the first control sequence section.

The set of instructions in the present computer-readable medium orwaveform may further comprise a first instruction to place a firstcontrol sequence section before a bulk portion of the information, asecond instruction to place a first group of the information bits afterthe first control sequence and before the bulk portion of theinformation, and a third instruction to place a second control sequencesection after the first group of the information bits and before thebulk portion of the information. In further embodiments, the set ofinstructions further comprises a fourth instruction to place a secondgroup of the information bits after the second control sequence andbefore the bulk portion of the information, and a fifth instruction toplace a third control sequence section after the second group of theinformation bits and before the bulk portion of the information. As onecan see, the number of additional instructions to place additionalgroups of information bits and control sequence section can increase toessentially any number, depending on the number of control sequencesections.

The present computer-readable medium or waveform may include certainboundaries on the control sequence and interleaved data. For example,the control sequence may have a length of n bits and may comprise msections, where each of n and m are independently an integer of at least2, n≧m, and each of the sections of the control sequence independentlyhas a length of from 1 to (n−m) bits. In one embodiment, n is an eveninteger of at least 4, m is an integer of from 2 to (n/2), and each ofthe control sequence section lengths is independently from 2 to (n/2)bits. Alternatively, n may be an odd integer of at least 5, m is aninteger of from 2 to ((n−1)/2), and each of the control sequence sectionlengths is independently from 2 to ((n+1)/2) bits. In other embodiments,4≦n≦40, 6≦n≦30, or 8≦n≦20, similar to the discussion above of certaincontrol sequence length variations. Furthermore, the interleaved bits ofinformation generally comprise (m−1) groups of the information bits,where each group independently has a length of up to p bits, wherein pis an integer of at least 2 and less than n (or any range of valuesbetween 2 and n).

With regard to the present method for receiving information from achannel having one or more time-dependent parameter fluctuations, thecomputer-readable medium or waveform may contain a set of instructionsthat further comprises at least one instruction to synchronize a firstbit of the block of information to a predetermined reference. Thepredetermined reference may be a predetermined point in time, apredetermined transition or logic level of a (reference) clock signal,or a first cycle of a counter configured to count the received bits ofinformation.

The set of instructions relating to the present method for receivinginformation may also further comprise (i) at least one instruction tosearch for (A) the control sequence (or a first control sequencesection) at a first bit position of the received information and (B) thecontrol sequence (or a second control sequence section) at a second bitposition of the received information; (ii) a subset of instructionsconfigured to compare or match a first control sequence section to afirst reference sequence section at each of the first and second bitpositions and compare or match a second control sequence section to asecond reference sequence section, where a first group of informationbits of known length is interposed between the first and second controlsequence sections; and/or (iii) an instruction to search for a preamblein the received information before the first control sequence section.In further embodiments, the set of instructions further comprises (iv) athird instruction to search for a third control sequence section after asecond group of the information bits interposed between the secondcontrol sequence section and the third control sequence section, and/or(v) an instruction to configured to compare or match a third controlsequence section to a third reference sequence section, where a secondgroup of information bits of known length is interposed between thesecond and third control sequence sections. Of course, the (sub)set ofinstructions to search, compare and/or match can be increased tocorrespond to the number of control sequence sections.

In even further embodiments, the present computer-readable medium orwaveform may further include (i) at least one instruction to calculate acorrelation coefficient (e.g., a minimum Hamming distance) for each bitposition in an information stream received during a control sequencesearch period, (ii) at least one instruction to compare bit positions inthe information corresponding to the first and second control sequencesections with a reference sequence, and/or (iii) at least oneinstruction to select the sequence at a bit position having the largestnumber of bits matching the reference sequence (or having the highestcorrelation coefficient or the lowest minimum correlation distance) asthe initial position of the control sequence.

Exemplary Circuits and Architectures

In one aspect, the present invention relates to a receiver, comprising:a recovery circuit configured to recover an information signal from achannel; a channel parameter monitor configured to determine, directlyor indirectly, a value for a channel parameter, the parameter havingperiodically recurring and/or time-dependant fluctuations; and logicconfigured to process the recovered information signal in a mannerdependent on the parameter value. In various embodiments, the channelcomprises a cyclostationary channel, and/or the time-dependant parameterfluctuation comprises a noise parameter, an energy parameter, a powerparameter, or an attenuation parameter. In one implementation, theparameter comprises transmission energy.

FIG. 7 shows an exemplary receiver 600 according to the presentinvention, comprising recovery circuit 610, channel parameter monitor620, and comparator 630. Both recovery circuit 610 and channel parametermonitor 620 receive information signal X as an input, along with certainorthogonal coefficient signals from the information input channel (orband) and the channel (or band) for which a time-dependent parameter isbeing monitored. Recovery circuit 610 and channel parameter monitor 620respectively provide demodulated (digital) information signal X_(n) andparameter instability signal r, as outputs (also see FIG. 6 forexemplary X_(n) and r_(n) waveforms).

For example, recovery circuit 610 may receive orthogonal and/orcomplementary phase coefficient signals sin(ω_(c)t) and cos(ω_(c)t) fromthe information input channel or band, and channel parameter monitor 620receives orthogonal and/or complementary transmission energy (or power)coefficient signals sin(ω_(ref)t) and cos(ω_(ref)t) from the referencechannel or band. Thus, the present receiver may receive inputs from (i)first and second cyclostationary channels of a common medium, or (ii)first and second bands of a common cyclostationary channel. In theformer case, the first and second cyclostationary channels are generallystructurally and/or functionally the same, and in the latter case, thefirst and second bands have different first and second frequencies orfrequency ranges, respectively. Of course, the transmission energycoefficient signals can be obtained from the information input channelor band, using inputs and logic that are well within the level of oneskilled in the art (e.g., by monitoring total transmission energy in theinformation input channel or band, and subtracting the informationsignal energy or strength therefrom).

The recovery circuit 610 may comprise conventional mathematical operatorcircuits or logic 612 a-612 b, filters 614 a-614 b, and demodulator 616.Mathematical operator circuits 612 a-612 b may comprise first and secondmultipliers (shown), or any mathematically equivalent circuit or logic.Mathematical operator circuits 612 a-612 b are generally configured to(i) receive the information signal and at least one reference signal(e.g., phase and/or transmission energy coefficient signals), and (ii)provide a down converted signal to the filter. Filters 614 a-614 b maycomprise first and second low pass filters, although one may use anycircuit or device providing the same or an equivalent function. Ingeneral, filters 614 a-b are configured to receive the informationsignal (or a modulated information signal) and provide a filteredinformation signal to the demodulator 616. In various embodiments, thedemodulator 616 comprises a phase shift keying (PSK) demodulator, suchas a differential binary PSK demodulator (shown in FIG. 7) or aquadrature PSK demodulator, although in certain applications (dependingon the signal modulation technique being used) one may employ afrequency shift keying (FSK) demodulator or a quadrature amplitudedemodulator. Although circuitry for processing a differentialinformation signal X is shown, the circuitry can be adapted to process asingle-ended information signal (in which case, a single mathematicaloperator and a single filter can be used). Similarly, the PSKdemodulator can also be coherent or non-coherent, and/or multiphaseinstead of binary, depending on the nature of the received informationsignal and/or the signal modulation technique(s) being used.

The channel parameter monitor 620 may comprise conventional mathematicaloperator circuits or logic 622 a-622 b, filters 624 a-624 b, and energycalculator 626. In the exemplary embodiment of FIG. 7, the channelparameter monitor (i) receives an input from a second channel or bandsubstantially similar to the transmission channel or band (i.e., fromwhich the information signal is received), and (ii) determines theparameter value of the second channel directly (generally in order toindirectly determine a value for the transmission channel or band).Mathematical operator circuits 622 a-622 b and filters 624 a-624 b maybe substantially identical in structure and/or function to themathematical operator circuits 612 a-612 b and filters 614 a-614 b inrecovery circuit 610. In the channel parameter monitor case, however,the mathematical operator circuit is generally configured to provide adown converted signal or a modulated parameter instability signal to thefilter, and the filter is generally configured to provide a filteredinformation signal (e.g., I_(n) or Q_(n)) to the energy calculator.Energy calculator 626 is generally configured to receive one or morefiltered signals from filters 614 a-614 b and provide an analog ormultibit digital parameter value signal (e.g., Energy signal 340 in FIG.4) in response thereto. In one embodiment, energy calculator 626calculates a channel energy signal value according to the equation:Energy=Σ(I _(n) ² +Q _(n) ²)  (1)where the sums are taken over a moving window of samples (e.g., using asample size of from 1 to 2^(n), 2 to 16, 3 to 8, and in oneimplementation, 4 samples) to provide a moving average energy in thesampled channel, although the invention is certainly not limited to thistechnique and/or circuitry for calculating channel energy.

In various embodiments of the receiver of FIG. 7, the logic configuredto process the recovered information signal in a manner dependent on theparameter value includes comparator 630, which is generally configuredto detect when the first parameter value exceeds a predeterminedthreshold and/or initiate or enable a function in response thereto. Forexample, the logic may be further configured to mark bits received fromthe first channel as unreliable when the first parameter value of thesecond channel exceeds a predetermined threshold (e.g., using noisemarking [or parameter instability] signal r_(n)).

Similarly, energy calculator 646 (which receives inputs from filters 614a-b in transmission channel 610) and comparator 650 (which receives anoutput signal from energy calculator 646) may be configured to (i)initiate a search for a control sequence in the information signal whenthe first parameter value exceeds a predetermined threshold (e.g., byasserting an active “SOP DETECT” signal 350); (ii) mark bits receivedfrom the first channel as unreliable when the first parameter valueexceeds a predetermined threshold; and/or (iii) carry out one or more ofthe searching, detecting, matching, determining, comparing and/orcalculating steps described with regard to identifying the controlsequence in the present method of receiving information. Energycalculator 646 and comparator 650 may be very similar to energycalculator 626 and comparator 630 in structure and/or function.

Alternatively, the present receiver may comprise means for recovering aninformation signal from a channel; means for directly or indirectlydetermining a value for a parameter of the channel, the parameter havingtime-dependant fluctuations; and means for processing the recoveredinformation signal in a manner dependent on the parameter value. Themeans for recovering may comprise a means for modulating the informationsignal, a means for filtering the modulated information signal, and/or ameans for demodulating the filtered, modulated information signal. Themeans for processing may comprise a means for detecting when theparameter value exceeds a predetermined threshold, a means foridentifying a control sequence in the information signal when theparameter value exceeds a predetermined threshold, a means for markingbits received from the channel as unreliable when the parameter valueexceeds a predetermined threshold, and/or a means for marking bitsreceived from the transmission channel as unreliable when the parametervalue of a second channel exceeds a predetermined threshold.

The means for directly or indirectly determining generally comprises ameans for comparing the parameter value to a threshold or referencevalue, and may further comprise a means for calculating the firstparameter value. In further embodiments, the means for directly orindirectly determining further comprises (i) a means for filtering theinformation signal (which may be configured to provide a filteredinformation signal to the means for calculating), (ii) a means forreceiving an input from a second channel substantially similar to thetransmission channel, (iii) a means for directly determining theparameter value of the second channel (to thereby indirectly determine avalue for the same parameter in the transmission channel), and/or (iv) ameans for modulating the information signal, configured to provide amodulated information signal to the means for filtering.

In another aspect of the present invention, the present receiver maycomprise: a recovery circuit configured to recover an information signalfrom a first channel having one or more time-dependant parameterfluctuations; a storage circuit configured to store a control sequencepattern comprising a plurality of interleaved sections; and logicconfigured to identify the control sequence pattern in the informationsignal. FIG. 8 shows a box-level diagram of an exemplary architecturefor such a receiver, comprising information recovery circuit 710,control sequence storage circuit 720, comparator 730 and informationprocessing logic 740. This receiver is particularly adapted forconducting the searching, determining, detecting, comparing and/ormatching processes of the present method of receiving informationdescribed above.

Recovery circuit 710 may be substantially similar or identical(structurally and/or functionally) to recovery circuit 610 of FIG. 7.For example, as for the exemplary receiver of FIG. 7, the recoverycircuit 710 in FIG. 8 may comprise a demodulator, such as a phase shiftkeying (PSK) demodulator (which may be differential or single ended), afilter (such as a low pass filter) configured to receive the informationsignal and provide a filtered information signal to the demodulator, anda mathematical operator circuit (such as a multiplier) configured to (i)receive the information signal and a reference signal, and (ii) providea modulated information signal to the filter.

Control sequence storage circuit 720 is typically a memory, such asvolatile memory (e.g., a DRAM array, an SRAM array, a set of flip-flops,one or more rows or banks of registers), nonvolatile memory (e.g., oneor more rows or arrays of EPROM, EEPROM, flash or magnetic memory), or acombination thereof (e.g., a row or array of EPROM or flash memory forlong-term storage that is written into a register bank during use of thereceiver 700). Notably, control sequence storage circuit 720 may furtherstore mask bits, representative of the interleaved information bits inthe received information stream, that are generally ignored duringcomparison with the received information signal (e.g., that have a valueequivalent to a “don't care” state in digital logic). The arrangementand/or sequence of control sequence sections and interleaved datasegments is substantially as discussed above with respect to the presentmethod(s).

The comparator 730 is generally configured to compare sequences from thereceived information signal to the control sequence stored in controlsequence storage circuit 720. Comparator 730 may further include logicconfigured to perform the searching, determining, detecting, comparingand/or matching processes of the present method of receiving informationdescribed above. For example, comparator 730 may further include logicconfigured to compare the control sequence pattern with different bitpositions in the recovered information and find or identify the positionhaving the largest correlation (or the smallest Hamming distance).

Logic 740 is generally configured to perform functions on the recoveredinformation signal, once the control sequence has been identified. Forexample, logic 740 may be configured to synchronize the block ofinformation to a reference (e.g., as discussed above) after the controlsequence is identified in the received information block.

Exemplary Transceivers, Systems and Networks

A further aspect of the invention relates to a transceiver, comprisingthe present receiver, and a transmitter in communication with thechannel. Generally, the transmitter is configured to transmitinformation to a network comprising the channel. Alternatively, thetransceiver comprises the present receiver and a means for transmittinginformation to the first channel.

FIG. 9 shows an exemplary transmitter 800 suitable for use inconjunction with the present invention. Transmitter 800 may includetransmitter logic 810, framer 820, interleaver 830, clock generator 840,counter 850, amplifier 860 and output driver 870. Without intending tobe so limited, each of the circuit blocks 810-870 is generallyconventional, and performs generally conventional functions associatedwith such circuits as understood by those skilled in the art. However,transmitter logic 810 generally receives a serial or parallel datastream DATA and performs certain functions on it, such as buffering and(if necessary) converting it into serial data for framer 820.Transmitter logic 810 is also generally configured to (i) identify oneor more reference locations in the data stream and/or (ii) count and/orsample bits of the incoming data stream DATA, and communicate controlinformation relating to data stream locations and/or lengths tointerleaver 830, which uses such information to perform (or instructframer 820 to perform) the functions described above with regard to thepresent method of transmitting information over a cyclostationarychannel.

In one embodiment, interleaver 830 comprises a shift register comprisingm rows each independently having a length of n bits (where each of n andm are as described above) configured to provide the control informationto be interleaved to framer 830 in response to timing signals from acounter that, in the embodiment of FIG. 9, is internal to interleaver830 and that receives a clock signal from clock generator 840.Alternatively, the timing signal for interleaver 830 to provide controlsequence sections to framer 820 may be generated by transmitter logic810 or counter/timer 850. Other than interleaving control sequences intothe information to be transmitted over the channel, framer 830 isgenerally conventional and performs its conventional function (e.g.,receiving a serial data stream from transmitter logic 810, a clocksignal from clock generator 840, and one or more timing signals fromcounter/timer block 850, and adding control information as describedabove in a conventional frame or data packet format for serialtransmission to amplifier 860).

The receiver and/or transceiver in the present system and/or network mayfurther comprise a conventional clock (recovery) circuit, configured toprovide a conventional clock signal to the transmitter and the receiver(or recover a clock signal from the received information), and/or othercircuitry conventionally associated with a data receiver. For example,the transceiver may further comprise a phase locked loop configured toprovide a reference clock signal to the transmitter and receiver. Infurther embodiments, the transceiver may be configured to convert serialinformation from the network to parallel information (e.g., data) for adevice, and/or convert parallel data from the device to serial data forthe network.

In one embodiment, the transceiver is embodied on a single integratedcircuit. Thus, when the system comprises a single-chip transceiver, thesystem may further comprise an internal transmitter (i.e., on the samechip as the present receiver) communicatively coupled to (i.e.,physically and/or electronically associated with) the present receiver,configured to transmit information (e.g., serial data) to the network.The system may also further comprise at least one receiver port externalto the receiver and/or transceiver, communicatively coupled to theinternal transmitter for receiving the information transmittedtherefrom.

In a further aspect, the present invention concerns a system fortransferring information on or across a network, comprising the presenttransceiver (described above) and at least one additional transmitterfor transmitting the information signal, wherein the additionaltransmitter is external to the transceiver. The system may furthercomprise a second receiver in communication with (and which may becommunicatively coupled to) the transceiver, configured to receiveinformation from the channel.

FIG. 10 shows an exemplary system 900, including first and secondtransceivers 910 and 920 and channel 930. Transceiver 910 includes firsttransmitter TX1 912 and first receiver RX1 914, and transceiver 920includes second transmitter TX2 922 and second receiver RX2 924.Transmitters 912 and 922 may be exemplified by transmitter 800 of FIG.9, and receivers 914 and 924 may be exemplified by receivers 600 and/or700 of FIGS. 7-8. Channel 930 typically comprises a cyclostationarychannel. Generally, transmitter TX1 912 transmits information overchannel 930 to receiver RX2 924 (and any other receiver that may be incommunication with channel 930), and transmitter TX2 922 transmitsinformation over channel 930 to receiver RX1 914 (and any other receiverthat may be in communication with channel 930).

In a further aspect, the present invention concerns a network,comprising a plurality of the present systems (described above), inelectromagnetic communication with each other, and a plurality ofstorage, information processing or communications devices (or,alternatively, means for storing, processing or further communicatingthe information signal). Generally, each of the storage, informationprocessing or communications devices are in electromagneticcommunication with (and may be communicatively coupled to) one of thesystems.

The network may be any kind of known network using a cyclostationarychannel, such as a storage network (e.g., RAID array), powerlinenetwork, or home network. Furthermore, the network may include any knownstorage or communications device, but preferably, at least a pluralityof the coupled devices comprise powerline communications and/or storagedevices, such as a personal computer, telephone, television, mediarecorder and/or player (such as a DVD player, a CD player), etc.

CONCLUSION/SUMMARY

Thus, the present invention provides a circuit, architecture, method,algorithm, software and system for improving or increasing thereliability of data communications using time diversity coding. Thistechnique is particularly useful in cyclostationary channels, wherecertain data communications parameters (such as noise and/or powerparameters) have time-dependent or periodic variations in value. Byassociating a reliability factor with each copy of the communicated datareceived during a time period when a channel parameter has atime-dependant parameter that may affect data reliability, intelligenttime diversity coding provides an increased probability that thecommunicated data is accurate and/or reliable.

The foregoing descriptions of specific embodiments of the presentinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise forms disclosed, and obviously manymodifications and variations are possible in light of the aboveteaching. The embodiments were chosen and described in order to bestexplain the principles of the invention and its practical application,to thereby enable others skilled in the art to best utilize theinvention and various embodiments with various modifications as aresuited to the particular use contemplated. It is intended that the scopeof the invention be defined by the Claims appended hereto and theirequivalents.

1. A method of communicating a block of information, the methodcomprising: interleaving a plurality of sections of a control sequencewith bits of said information; transmitting said interleaved controlsequence sections and said block of information over a cyclostationarychannel having periodically recurring and/or time-dependent noise,energy, or power fluctuations; receiving said block of information fromsaid channel; identifying said interleaved control sequence sections;comparing a transmission energy from a second channel with a thresholdenergy, said second channel being proximate to said cyclostationarychannel and having at least one substantially similar periodicallyrecurring and/or time-dependent noise, energy, or power fluctuation tothose of said cyclostationary channel; and processing said block ofinformation.
 2. The method of claim 1, wherein said block of informationcomprises a packet or frame comprising data.
 3. The method of claim 1,wherein said control sequence comprises a preamble, a synchronizationmark, a header sequence, a start-of-frame sequence, a start-of-packetsequence, address information, encryption information, an error checkingsequence or an identification sequence.
 4. The method of claim 1,wherein said control sequence comprises a synchronization mark.
 5. Themethod of claim 4, further comprising: identifying said synchronizationmark; and synchronizing a first bit of said block of information to apredetermined reference.
 6. The method of claim 1, wherein said sectionsof said control sequence are interleaved with bits of said informationfor at least one-third of a period of said periodically recurring and/ortime-dependent noise, energy, or power fluctuations.
 7. The method ofclaim 1, further comprising comparing said transmitted control sequenceto a reference sequence.
 8. The method of claim 1, wherein said block ofinformation further comprises a preamble, and said method furthercomprises transmitting said preamble.
 9. The method of claim 1, whereinsaid cyclostationary channel has periodically recurring and/or timedependent noise fluctuations.
 10. A computer-readable medium comprisingcomputer-executable instructions stored thereon which, when executed bya processing device, is adapted to perform the method of claim
 1. 11.The computer-readable medium of claim 10, wherein said block ofinformation comprises (i) a preamble and (ii) a packet or framecomprising data, and said control sequence comprises a synchronizationmark, a header sequence, a start-of-frame sequence, a start-of-packetsequence, address information, encryption information, an error checkingsequence or an identification sequence.
 12. The computer-readable mediumof claim 11, wherein said control sequence comprises a synchronizationmark.
 13. The computer-readable medium of claim 10, wherein said set ofinstructions further comprises: a first instruction to place a firstcontrol sequence section before a bulk portion of said information; asecond instruction to place a first group of said information bits aftersaid first control sequence and before said bulk portion of saidinformation; and a third instruction to place a second control sequencesection after said first group of said information bits and before saidbulk portion of said information.
 14. The computer-readable medium ofclaim 13, wherein said set of instructions further comprises: a fourthinstruction to place a second group of said information bits after saidsecond control sequence and before said bulk portion of saidinformation; and a fifth instruction to place a third control sequencesection after said second group of said information bits and before saidbulk portion of said information.
 15. The computer-readable medium ofclaim 13, wherein said instructions are configured to perform the stepof placing a preamble before said first control sequence section. 16.The computer-readable medium of claim 10, wherein said control sequencehas a length of n bits and comprises m sections, wherein 4≦n≦40, m is aninteger of at least 2, n≧m, and each of said sections of said controlsequence independently has a length of from 1 to (n−m) bits.
 17. Themethod of claim 4, wherein said block of information comprises a packetor frame comprising data.
 18. The method of claim 2, wherein saidcontrol sequence comprises a preamble, a synchronization mark, a headersequence, a start-of-frame sequence, a start-of-packet sequence, addressinformation, encryption information, an error checking sequence or anidentification sequence.
 19. The method of claim 18, wherein saidcontrol sequence comprises a synchronization mark.
 20. The method ofclaim 19, further comprising: identifying said synchronization mark; andsynchronizing a first bit of said block of information to apredetermined reference.
 21. The method of claim 5, further comprisingsearching for said interleaved sections of said control sequence inresponse to a transmission energy exceeding a threshold energy.
 22. Themethod of claim 21, wherein searching for said interleaved sectionscomprises calculating a correlation coefficient and/or a minimumcorrelation distance between (i) one or more sequences of said block ofinformation and (ii) a reference sequence comprising known values andlocations of said interleaved sections of said control sequence.
 23. Themethod of claim 21, wherein searching for said interleaved sectionsfurther comprises the steps of (i) comparing one or more sequences ofsaid block of information with a reference sequence comprising knownvalues and locations of said interleaved sections of said controlsequence, and (ii) selecting one of said one or more sequences of saidblock of information having a largest number of matching bits as saidcontrol sequence.
 24. The method of claim 21, wherein searching for saidinterleaved sections is conducted for at least an integer fraction of aperiod of said periodically recurring and/or time-dependent noise,energy, or power fluctuations.
 25. The method of claim 1, furthercomprising marking bits received from said cyclostationary channel asunreliable when said transmission energy from said second channelexceeds said threshold energy.
 26. The method of claim 25, furthercomprising identifying said interleaved sections of said controlsequence from unmarked bits in said information received from saidcyclostationary channel.
 27. A computer-readable medium comprisingcomputer-executable instructions stored thereon which, when executed bya processing device, is adapted to perform the method of claim
 4. 28. Asystem for transferring information on or across a network, the systemcomprising: a transmitter configured to (i) interleave a plurality ofsections of a control sequence with bits of a block of said information;and (ii) transmit said block of information and said interleaved controlsequence sections; said transmitter comprising: an interleaverconfigured to interleave or instruct another circuit in said transmitterto interleave, said plurality of control sequence sections with saidinformation bits; a framer configured to receive a serial data streamand add said control sequence sections to said serial data stream; logicconfigured to provide said serial data stream to said framer; a clockgenerator configured to provide a clock signal to at least one of saidinterleaver, said framer and said logic; and a counter configured toreceive said clock signal and provide a timing signal to at least one ofsaid framer and said interleaver; and a cyclostationary channel incommunication with said transmitter, wherein the cyclostationary channelhas periodically recurring and/or time-dependant noise, energy, or powerfluctuations.
 29. The system of claim 28, wherein said cyclostationarychannel has periodically recurring and/or time-dependent noisefluctuations.
 30. The system of claim 28, wherein said transmitter isfurther configured to interleave said sections of said control sequencewith bits of said information for at least one-third of a period of saidperiodically recurring and/or time-dependent parameter fluctuations. 31.The system of claim 28, wherein said block of information comprises apacket or frame comprising data.
 32. The system of claim 28, whereinsaid control sequence comprises a preamble, a synchronization mark, aheader sequence, a start-of-frame sequence, a start-of-packet sequence,address information, encryption information, an error checking sequenceor an identification sequence.
 33. The system of claim 32, wherein saidcontrol sequence comprises a synchronization mark.
 34. The system ofclaim 28, wherein said interleaver comprises a shift register configuredto store said plurality of control sequence sections.
 35. A system fortransferring information on or across a network, the system comprising:means for transmitting a block of said information, said block ofinformation having a plurality of interleaved sections of a controlsequence therein, said means for transmitting comprises: means forinterleaving said plurality of control sequence sections with bits ofsaid block of information; means for framing a serial data stream andadding said control sequence sections to said serial data stream; meansfor providing said serial data stream to said means for framing; meansfor generating a clock signal for at least one of said means forinterleaving, said means for framing and said means for providing; andmeans for providing a timing signal to at least one of said means forframing and said means for interleaving; and means for communicatingsaid block of information to means for receiving said block ofinformation, wherein said means for communicating has periodicallyrecurring and/or time-dependent noise, energy, or power fluctuations.36. The system of claim 35, wherein said means for communicating hasperiodically recurring and/or time-dependent noise fluctuations.
 37. Thesystem of claim 35, wherein said means for transmitting comprises ameans for interleaving said sections of said control sequence with bitsof said information for at least one-third of a period of saidperiodically recurring and/or time-dependent parameter fluctuations. 38.The system of claim 35, wherein said block of information comprises apacket or frame comprising data.
 39. The system of claim 35, whereinsaid control sequence comprises a preamble, a synchronization mark, aheader sequence, a start-of-frame sequence, a start-of-packet sequence,address information, encryption information, an error checking sequenceor an identification sequence.
 40. The system of claim 39, wherein saidcontrol sequence comprises a synchronization mark.
 41. The system ofclaim 35, wherein said means for interleaving comprises a shift registerconfigured to store said plurality of control sequence sections.
 42. Atransmitter configured to transmit information to a network comprising acyclostationary channel, the transmitter comprising: a framer configuredto receive a serial data stream and a plurality of control sequencesections and output a block of information; an interleaver configured tointerleave said control sequence sections and said serial data streaminto said block of information; a counter configured to receive a clocksignal and provide a timing signal to at least one of said framer andsaid interleaver; and a driver configured to modulate said block ofinformation onto said cyclostationary channel, said cyclostationarychannel having periodically recurring and/or time-dependent noise,energy, or power fluctuations.
 43. The transmitter of claim 42, furthercomprising logic configured to provide said serial data stream to saidframer.
 44. The transmitter of claim 43, further comprising a clockgenerator configured to provide a clock signal to at least one of saidinterleaver, said framer and said logic.
 45. The transmitter of claim42, wherein said block of information comprises a packet or framecomprising data.
 46. The transmitter of claim 42, wherein said controlsequence comprises a preamble, a synchronization mark, a headersequence, a start-of-frame sequence, a start-of-packet sequence, addressinformation, encryption information, an error checking sequence or anidentification sequence.
 47. The transmitter of claim 42, wherein saidcontrol sequence comprises a synchronization mark.
 48. The transmitterof claim 42, wherein said sections of said control sequence areinterleaved with bits of said information for at least one-third of aperiod of said periodically recurring and/or time-dependent parameterfluctuations.
 49. The transmitter of claim 42, wherein said block ofinformation further comprises a preamble.
 50. The transmitter of claim42, wherein said cyclostationary channel has periodically recurringand/or time-dependant noise fluctuations.
 51. A transceiver, comprising:a transmitter in communication with a first cyclostationary channel,configured to transmit information to a network comprising said firstcyclostationary channel, said transmitter comprising: a framerconfigured to receive a serial data stream and a plurality of controlsequence sections and output a block of information; an interleaverconfigured to interleave said control sequence sections and said serialdata stream into said block of information; and a driver configured tomodulate said block of information onto said first cyclostationarychannel; and a receiver comprising: a recovery circuit configured torecover an information signal from said first cyclostationary channel; achannel parameter monitor configured to determine, directly orindirectly, a value for a first parameter of said first cyclostationarychannel, said first parameter having one or more periodically recurringand/or time-dependant fluctuations; and logic configured to process saidrecovered information signal in a manner dependent on said firstparameter value.
 52. The transceiver of claim 51, wherein said one ormore periodically recurring and/or time-dependant parameter fluctuationscomprise a noise parameter, an energy parameter, a power parameter, oran attenuation parameter.
 53. The transceiver of claim 51, wherein saidrecovery circuit comprises a demodulator.
 54. The transceiver of claim53, wherein said demodulator comprises a phase shift keying (PSK)demodulator.
 55. The transceiver of claim 53, wherein said recoverycircuit further comprises a filter configured to receive saidinformation signal and provide a filtered information signal to saiddemodulator.
 56. The transceiver of claim 55, wherein said recoverycircuit further comprises a mathematical operator configured to (i)receive said information signal and a reference signal, and (ii) providea modulated information signal to said filter.
 57. The transceiver ofclaim 51, wherein said logic of said receiver is configured to detectwhen said first parameter value exceeds a predetermined threshold. 58.The transceiver of claim 57, wherein said logic of said receiver isfurther configured to initiate a search for a control sequence in saidinformation signal when said first parameter value exceeds apredetermined threshold.
 59. The transceiver of claim 57, wherein saidlogic of said receiver is configured to mark bits received from saidfirst cyclostationary channel as unreliable when said first parametervalue exceeds a predetermined threshold.
 60. The transceiver of claim57, wherein said channel parameter monitor (i) receives an input from asecond cyclostationary channel substantially similar to said firstcyclostationary channel, and (ii) determines directly said firstparameter value of said second cyclostationary channel.
 61. Thetransceiver of claim 60, wherein said logic of said receiver isconfigured to mark bits received from said first cyclostationary channelas unreliable when said first parameter value of said secondcyclostationary channel exceeds a predetermined threshold.
 62. Thetransceiver of claim 60, wherein said channel parameter monitorcomprises a comparator.
 63. The transceiver of claim 62, wherein saidchannel parameter monitor further comprises an energy calculator. 64.The transceiver of claim 63, wherein said channel parameter monitorfurther comprises a filter configured to receive said information signaland provide a filtered channel parameter signal to said energycalculator.
 65. The transceiver of claim 64, wherein said channelparameter monitor further comprises a mathematical operator configuredto (i) receive said information signal and a reference signal, and (ii)provide a modulated channel parameter signal to said filter.
 66. Thetransceiver of claim 51, embodied on a single integrated circuit. 67.The transceiver of claim 51, further comprising a phase locked loopconfigured to provide a reference clock signal to said transmitter andsaid receiver.
 68. A system for transferring information on or across anetwork, the system comprising: the transceiver of claim 51; and atleast one external transmitter external to said transceiver, fortransmitting said information signal.
 69. The system of claim 68,further comprising a external receiver external to said transceiver incommunication with said transceiver, configured to receive informationfrom said first cyclostationary channel.
 70. A network, comprising: aplurality of the systems of claim 68, in communication with each other;and a plurality of storage, information processing or communicationsdevices, each of said storage, information processing or communicationsdevices being in communication with one of said systems.
 71. Atransceiver, comprising: a transmitter communicatively coupled to achannel configured to transmit information to a network comprising saidchannel, the transmitter comprising: a framer configured to receive aserial data stream and a plurality of control sequence sections andoutput a block of information; an interleaver configured to interleavesaid control sequence sections and said serial data stream into saidblock of information; a driver configured to modulate said block ofinformation onto the channel, the channel having periodically recurringand/or time-dependent parameter fluctuations, and a receiver comprising:a recovery circuit configured to recover an information signal from thechannel; a storage circuit configured to store a control sequencepattern comprising a plurality of interleaved sections; and logicconfigured to identify said control sequence pattern in said informationsignal.
 72. The transceiver of claim 71, wherein said channel comprisesa cyclostationary channel.
 73. The transceiver of claim 71, wherein saidchannel has periodically recurring and/or time-dependant noise, energy,or power fluctuations.
 74. The transceiver of claim 71, wherein saidlogic of said receiver is configured to synchronize said informationsignal to a reference.
 75. The transceiver of claim 71, wherein thereceiver further comprises a comparator configured to determine whensaid first parameter value exceeds a predetermined threshold, whereinsaid logic of said receiver is configured to initiate identifying saidcontrol sequence pattern in response to said first parameter valueexceeding a predetermined threshold.
 76. The transceiver of claim 71,embodied on a single integrated circuit.
 77. A system for transferringinformation on or across a network, the system comprising: thetransceiver of claim 71; and at least one external transmitter externalto said transceiver for transmitting said information signal.
 78. Thesystem of claim 77, further comprising an external receiver external tosaid transceiver in communication with said transceiver, configured toreceive information from said channel.
 79. A network, comprising: aplurality of the systems of claim 77, in communication with each other;and a plurality of storage, information processing or communicationsdevices, each of said storage, information processing or communicationsdevices being in communication with one of said systems.